Engine oil lubricant compostions and methods for making same with steel corrosion protection

ABSTRACT

Provided is a low sulfated ash engine oil lubricant composition containing organic friction modifiers with improved fuel economy and corrosion resistance. The lubricant composition includes one or more metal free corrosion inhibitors having an organic acid group and/or one or more organo metallic naphthalene molecules having a ASTM D2896 total base number less than 3 mg KOH/g. The resulting lubricant composition improves ASTM D6557 corrosion protection for low sulfated ash engine oils containing organic friction modifiers, while maintaining exceptional fuel economy performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/110,716, filed on Nov. 6, 2020, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to low sulfated ash engine oil lubricant compositions and methods for making same. Such compostions are useful for gasoline and diesel engines and provide a combination of excellent aftertreatment device protection, steel corrosion protection, and fuel efficiency.

DESCRIPTION OF THE RELATED ART

A major challenge in engine oil formulation is simultaneously achieving aftertreatment device protection while also maintaining fuel economy performance and providing steel corrosion protection.

Fuel efficiency requirements for passenger vehicles are becoming increasingly more stringent. The combustion of 1 gallon of gasoline produces about 19.5 pounds of carbon dioxide (CO₂). So technology that improves fuel economy (i.e. more miles per gallon of combustion) will necessarily reduce CO₂ emissions. New legislation in the United States and European Union within the past few years has set fuel economy and carbon emissions targets not readily achievable with today's vehicle and lubricant technology. In Europe, for example, CO₂ emission requirements for gasoline passenger cars have dropped from 130 g CO₂/km in 2015 to 95 in 2021, to 81 in 2025 and to 59 in 2030. Due to these more stringent governmental regulations for vehicle fuel consumption and carbon emissions, use of passenger car diesel engines or gasoline direct injection engines, or gasoline hybrid engines are becoming more prevalent.

To meet the future carbon dioxide emission requirements, engine oil formulations often contain organic friction modifiers to help reduce friction, which helps improves engine efficiency and fuel economy. A major challenge in engine oil formulations containing organic friction modifiers, however, is the high surface activity that can lead to more corrosion, which leads to engine inefficiencies and thus lower fuel economy.

Another major challenge in engine oil formulations is aftertreatment device durability. Diesel Particulate Filters (DPFs) and Gasoline Particulate Filters (GPFs), for example, are exhaust aftertreatment devices used to control particulate matter and particulate number emissions and are negatively impacted by metallic species contained in engine oil formulations. Sulfated Ash (ASTM D874) is a common measure of the metals content of an engine oil formulation. In the ASTM D874 test, an engine oil is evaporated to a residue and then reacted with sulfuric acid at 775° C. This converts metals calcium (Ca), magnesium (Mg), zinc (Zn), molybdenum (Mo), sodium (Na) in the residue to a sulfated “ash”, which is then weighed.

To provide aftertreatment device durability, engine oils are typically formulated to have ≤1.0 wt % ash or 0.9 wt % ash or 0.8 wt % ash or 0.5 wt % of sulfated ash. A major source of the sulfated ash is from metallic detergents that are used to provide piston cleanliness and neutralize acids that are formed from combustion. As ash levels are reduced, metallic detergent levels are also reduced, which limits the ability of an engine oil to neutralize acidic species.

There is a need, therefore, for improved engine oil formulations capable of achieving aftertreatment device protection while also providing fuel economy performance and steel corrosion protection.

SUMMARY

Low sulfated ash engine oil lubricant compositions are provided. The engine oil lubricant compositions can have a sulfated ash content of 0.5 wt % or less, and an HTHS (ASTM D4683) of less than or equal to 3.7 cP at 150° C. In at least one specific embodiment, the composition can include about 40 wt % to about 90 wt % of at least one base oil, about 0.1 wt % to about 5 wt % of an organic friction modifier, about 1 wt % to about 6 wt % of at least one detergent comprising magnesium or calcium, and about 0.01 wt % to about 1 wt % of a corrosion inhibitor having at least one organic acid or organic salt group. In at least one other specific embodiment, the composition can include about 40 wt % to about 90 wt % of at least one base oil, about 0.1 wt % to about 5 wt % of an organic friction modifier, about 1 wt % to about 6 wt % of at least one detergent comprising magnesium or calcium, and about 0.01 wt % to about 1 wt % of a corrosion inhibitor comprising an organo-metallic naphthalene compound.

DETAILED DESCRIPTION

It has been surprisingly discovered that metal free corrosion inhibitors having an organic acid or organic salt group can improve ASTM D6557 corrosion protection for low sulfated ash engine oils containing organic friction modifiers, while maintaining exceptional fuel economy performance. It has also been surprisingly discovered that organo metallic naphthalene molecules having a ASTM D2896 total base number less than 3 mg KOH/g can improve ASTM D6557 corrosion protection for low sulfated ash engine oils containing organic friction modifiers, while maintaining exceptional fuel economy performance.

The ASTM D6557 test is a steel corrosion test where a 5.6 mm diameter steel ball is placed in a test tube with 10 mL of engine oil. The test tube with engine oil and steel ball is then placed on a mechanical shaker. An acid mixture of hydrochloric acid (HCl), hydrobromic acid (HBr), and acetic acid is continuously added to the test tube. The test is conducted for 18 hours at 48° C. Afterwhich, the steel ball is removed, rinsed, and the reflectivitiy of the ball is measured. New balls have a reflectivity of about 133 average gray value units (“AGV”). A reduction in average gray value indicates that corrosion has occurred.

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of” means that the described/claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass %. The term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein. The term “wt %” means percentage by weight, “vol %” means percentage by volume, “mol %” means percentage by mole, “ppm” means parts per million, and “ppm wt” and “wppm” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.

Base Oils

Lubricating base oils that are useful in the present disclosure are both natural oils, and synthetic oils, and unconventional oils (or mixtures thereof) can be used unrefined, refined, or rerefined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one lubricating oil property. One skilled in the art is familiar with many purification processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation. Rerefined oils are obtained by processes analogous to refined oils but using an oil that has been previously used.

Groups I, II, III, IV and V are broad categories of base oil stocks developed and defined by the American Petroleum Institute (API Publication 1509; www.AP1.org) to create guidelines for lubricant base oils. Group I base stocks generally have a viscosity index of between about 80 to 120 and contain greater than about 0.03% sulfur and/or less than about 90% saturates. Group II base stocks generally have a viscosity index of between about 80 to 120, and contain less than or equal to about 0.03% sulfur and greater than or equal to about 90% saturates. Group III stocks generally have a viscosity index greater than about 120 and contain less than or equal to about 0.03% sulfur and greater than about 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stock includes base stocks not included in Groups I-IV.

Non-limiting exemplary Group V base stocks include alkylated naphthalene base stock, ester base stock, aliphatic ether base stock, aryl ether base stock, ionic liquid base stock, and combinations thereof.

TABLE 1 Base oil properties of each of these five groups. Viscosity Saturates Sulfur Index Group I <90 &/or  >0.03% & ≥80 & < 120 Group II ≥90 & ≤0.03% & ≥80 & < 120 Group III ≥90 & ≤0.03% & ≥120 Group IV Includes polyalphaolefins (PAO) Group V All other base oil stocks not included in Groups I, II, III, or IV

Base Oil Properties

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Of the natural oils, mineral oils are preferred. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked basestocks, including synthetic oils such as polyalphaolefins, alkyl aromatics and synthetic esters are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from about 250 g/mol to about 3,000 g/mol, although PAO's may be made in viscosities up to about 100 cSt (100° C.). The PAOs are typically comprised of relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include, but are not limited to, C₂ to about C₃₂ alphaolefins with the C₈ to about C₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like, being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of C₁₄ to C₁₈ may be used to provide low viscosity basestocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs may be predominantly trimers and tetramers of the starting olefins, with minor amounts of the higher oligomers, having a viscosity range of 1.5 to 12 cSt (100° C.).

The PAO fluids may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example the methods disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C₁₄ to C₁₈ olefins are described in U.S. Pat. No. 4,218,330.

The hydrocarbyl aromatics can be used as base oil or base oil component and can be any hydrocarbyl molecule that contains at least about 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The aromatic can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can also be comprised of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl groups can range from about C₆ up to about C₆₀ with a range of about C₈ to about C₂₀ often being preferred. A mixture of hydrocarbyl groups is often preferred, and up to about three such substituents may be present. The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least about 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at 100° C. of approximately 1.8 cSt to about 50 cSt are preferred, with viscosities of approximately 2.2 cSt to about 20 cSt often being more preferred for the hydrocarbyl aromatic component. In one embodiment, an alkyl naphthalene where the alkyl group is primarily comprised of 1-hexadecene is used. Other alkylates of aromatics can be advantageously used. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like. Useful concentrations of hydrocarbyl aromatic in a lubricant oil composition can be about 2% to about 25%, preferably about 4% to about 20%, and more preferably about 4% to about 15%, depending on the application.

Esters comprise a useful base stock. Additive solvency and seal compatibility characteristics may be secured by the use of esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least about 4 carbon atoms, preferably C₅ to C₃₀ acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Suitable synthetic ester components include the esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipentaerythritol with one or more monocarboxylic acids containing from about 5 to about 10 carbon atoms. These esters are widely available commercially, for example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.

Other useful fluids of lubricating viscosity include non-conventional or unconventional base stocks that have been processed, preferably catalytically, or synthesized to provide high performance lubrication characteristics.

Non-conventional or unconventional base stocks/base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks.

The base oil constitutes the major component of the engine oil lubricant composition and typically is present in an amount ranging from about 50 to about 99 wt %, e.g., from 70 to 90 wt % or from about 85 to about 95 wt %, based on the total weight of the composition. The base oil may be selected from any of the synthetic or natural oils typically used as crankcase lubricating oils for spark-ignited and compression-ignited engines. The base oil has a kinematic viscosity, according to ASTM standards, of about 1.0 cSt to about 16.0 cSt (100° C.), preferably of about 1.0 cSt to about 12.0 cSt (100° C.), more preferably of about 2.0 cSt to about 8.0 cSt (100° C.) and even more preferably of about 2.0 cSt to about 4.0 cSt (100° C.). Mixtures of synthetic and natural base oils may be used if desired. As used herein, the base stock name is associated with the ASTM D445 kinematic viscosity at 100° C. of the base stock. For instance, PAO 4 has an ASTM D445 100° C. kinematic viscosity of 4 cSt; GTL 3 has a D445 100° C. kinematic viscosity of 3 cSt.

The engine oil lubricant composition of the present invention can have an ASTM D4683 High Temperature High Shear (HTHS) viscosity of less than or equal to 3.7 cP at 150° C., or less than or equal to 2.9 cP at 150° C., or less than or equal to 2.6 cP at 150° C., or less than or equal to 2.3 cP at 150° C., and preferably about 2.6 cP at 150° C. HTHS viscosity is the measure of a lubricant's viscosity under severe engine conditions, is measured using ASTM D4683.

Viscosity Modifiers (VM)

Viscosity modifiers are also known as VI improvers, viscosity index improvers and viscosity improvers. Suitable viscosity modifiers provide lubricants with high temperature and low temperature operability. Suitable viscosity modifiers also impart shear stability at elevated temperatures and acceptable viscosity at low temperatures. Suitable viscosity modifiers may be or may include one or more linear or star-shaped polymers and/or copolymers of methacrylate, butadiene, olefins, isoprene or alkylated styrenes, polyisobutylene, polymethacrylate, ethylene-propylene, hydrogenated block copolymer of styrene and isoprene, polyacrylates, styrene-isoprene block copolymer, styrene-butadiene copolymer, ethylene-propylene copolymer, hydrogenated star polyisoprene, and combinations thereof.

As used herein, the term “polymer” refers to any two or more of the same or different repeating units/mer units or units. The term “homopolymer” refers to a polymer having units that are the same. The term “copolymer” refers to a polymer having two or more units that are different from each other, and includes terpolymers and the like. The term “terpolymer” refers to a polymer having three units that are different from each other. The term “different” refers to units indicates that the units differ from each other by at least one atom or are different isomerically. Likewise, the definition of polymer, as used herein, includes homopolymers, copolymers, and the like. Furthermore, the term “styrenic block copolymer” refers to any copolymer that includes units of styrene and a mid-block.

Suitable olefin copolymers, for example, are commercially available from Chevron Oronite Company LLC under the trade designation “PARATONE®” (such as “PARATONE® 8921” and “PARATONE® 8941”); from Afton Chemical Corporation under the trade designation “HiTEC®” (such as “HiTEC® 5850B”); and from The Lubrizol Corporation under the trade designation “Lubrizol® 7067C”. Suitable polyisoprene polymers, for example, are commercially available from Infineum International Limited, e.g. under the trade designation “SV200”. Suitable diene-styrene copolymers, for example, are commercially available from Infineum International Limited, e.g. under the trade designation “SV 260”.

One particularly suitable viscosity modifier is polyisobutylene. Another particularly suitable viscosity modifier is polymethacrylate, which can also serve as pour point depressant. Other particularly suitable viscosity modifiers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates. Specific examples include styrene-isoprene and styrene-butadiene based polymers of 50,000 g/mol to 200,000 g/mol molecular weight.

Suitable viscosity modifiers may further include high molecular weight hydrocarbons, polyesters and dispersants that function as both a viscosity modifier and a dispersant. Typical molecular weights of these polymers may range between about 10,000 g/mol and about 2,000,000 g/mol, more typically about 20,000 g/mol and about 1,500,000 g/mol, and even more typically between about 50,000 g/mol and about 1,200,000 g/mol.

At least one viscosity modifier may be included in the engine oil lubricant composition at a concentration of from 0.1 to 5 wt %, or 0.1 to 8 wt %, or 0.1 to 14 wt %, or 0.5 to 10 wt %, or 0.01 to 2 wt %, or 1.0 to 7.5 wt %, or 1.5 to 5 wt %. At least one viscosity modifier may also be included in the engine oil lubricant composition at a concentration ranging from a low of about about 0.1 wt %, about 0.3 wt %, or about 0.5 wt % to a high of about 5 wt %, about 8 wt %, or about 16 wt %. At least one viscosity modifier concentration may also range from a low of about about 0.1 wt %, about 0.5 wt %, or about 1.0 wt % to a high of about 8 wt %, about 12 wt %, or about 14 wt %. The foregoing viscosity modifier concentrations are based on a polymer concentrate basis in terms of the total weight of the lubricating composition.

Friction Modifiers (FM)

A friction modifier is any material or two or more materials that can alter the coefficient of friction of a surface lubricated by a lubricant or fluid containing such material(s). Friction modifiers, also known as friction reducers, or lubricity agents or oiliness agents, and other such agents that change the ability of base oils, formulated lubricant compositions, or functional fluids, to modify the coefficient of friction of a lubricated surface may be effectively used in combination with the base oils or lubricant compositions of the present invention if desired. Friction modifiers that lower the coefficient of friction are particularly advantageous in combination with the base oils and lube compositions of this invention. Friction modifiers may include metal-containing compounds or materials as well as ashless compounds or materials, or mixtures thereof. Metal-containing friction modifiers may include metal salts or metal-ligand complexes where the metals may include alkali, alkaline earth, or transition group metals. Such metal-containing friction modifiers may also have low-ash characteristics. Transition metals may include molybdenum (Mo), antimony (Sb), tin (Sn), iron (Fe), copper (Cu), zinc (Zn), and others. Such suitable ligands may include hydrocarbyl derivative of alcohols, polyols, glycerols, partial ester glycerols, thiols, carboxylates, carbamates, thiocarbamates, dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides, imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and other polar molecular functional groups containing effective amounts of oxygen (O), nitrogen (N), sulfur (S), or phosphorus (P), individually or in combination.

Ashless friction modifiers can also be used. Suitable ashless friction modifiers may include hydroxyl-containing hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives, fatty organic acids, fatty amines, and sulfurized fatty acids. Fatty acids include short-chain fatty acids, medium-chain fatty acids, long-chain fatty acids, and very long-chain fatty acids. Short-chain fatty acids have carbon chains of between one and five carbon atoms. Medium-chain fatty acids have carbon chains of between six and twelve carbon atoms. Long-chain fatty acids have carbon chains of between thirteen and and twenty-one carbon atms. Very long-chain fatty acids have carbon chains greater than twenty-one carbons. These carbon chains can be saturated or unsaturated. Suitable ashless friction modifiers may also include lubricant materials that contain effective amounts of polar groups, for example, hydroxyl-containing hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives, and the like. Suitable ashless friction modifiers may include alkyl or alkylene fatty acid esters of glycerides, alkyl or alkylene glyceride esters. Polar groups in friction modifiers may include hydrocarbyl groups containing effective amounts of oxygen (O), nitrogen (N), sulfur (S), or phosphorus (P), individually or in combination. Other friction modifiers that may be particularly effective include, for example, salts (both ash-containing and ashless derivatives) of fatty acids, fatty alcohols, fatty amides, fatty esters, hydroxyl-containing carboxylates, and comparable synthetic long-chain hydrocarbyl acids, alcohols, amides, esters, hydroxy carboxylates, and the like. In some instances fatty organic acids, fatty amines, and sulfurized fatty acids may be used as suitable friction modifiers. In some instances, friction modifiers containing ethylene-oxide, oligomers of ethylene oxide, or polymer segments of ethylene oxide are effective.

Ashless friction modifiers may be or may include polymeric and/or non-polymeric molecules. A suitable polymeric friction modifier may have a weight average molecular weight (Mw) of 3,000 g/mol or more; 4,000 g/mol or more; 5,000 g/mol or more; 6,000 g/mol or more; 7,000 g/mol or more; 8,000 g/mol or more; 9,000 g/mol or more; 10,000 g/mol or more; 15,000 g/mol or more; 20,000 g/mol or more; 30,000 g/mol or more; 40,000 g/mol or more; or 45,000 g/mol or more. The molecular weight of suitable polymeric friction modifiers may also range from a low of about 3,000 g/mol, about 4,000 g/mol, or about 5,000 g/mol to a high of about 10,000 g/mol; about 30,000 g/mol, or about 50,000 g/mol. The molecular weight of suitable polymeric friction modifiers may also range from about 3,000 g/mol to 15,000 g/mol; about 4,000 g/mol to about 12,000 g/mol; about 3,000 g/mol to about 9,000 g/mol; about 3,000 g/mol to about 7,000 g/mol. The molecular weight of suitable polymeric friction modifiers may also be about 3,000 g/mol, about 4,000 g/mol, about 5,000 g/mol, about 6,000 g/mol, about 7,000 g/mol, about 8,000 g/mol, or about 9,000 g/mol. A particularly suitable polymeric friction modifier is or includes ethylene oxide (EtO), oligomers of ethylene oxide, or polymers of ethylene oxide.

Other Additives

The engine oil lubricant composition may also include one or more other additives typical for engine oils. These other additives may include any one or more anti-wear additives, dispersants, detergents, antioxidants, pour point depressant, corrosion inhibitors, anti-rust additives, metal deactivators, seal compatibility additives, and anti-foam agents. These other additives may be provided to the lubricant composition in the form of an additive package. The additive packages may be incorporated into the engine lubricant compositions at loadings of about 9 wt % to about 15 wt %, or about 10 to about 14.5 wt %, or about 11 to about 14 wt %, based on the total weight of the composition. The additive packages may also be incorporated into the engine lubricant compositions at loadings ranging from a low of about 5 wt %, about 7 wt %, about 9 wt %, or about 10 wt % to a high of about 11 wt %, about 14 wt %, about 14.5 wt %, or about 15 wt %, based on the total weight of the composition.

Antiwear

While there are many different types of antiwear additives, for several decades the principal antiwear additive for internal combustion engine crankcase oils is a metal alkylthiophosphate and more particularly a metal dialkyldithiophosphate in which the metal constituent is zinc, or zinc dialkyldithiophosphate (ZDDP). ZDDP can be primary, secondary or mixtures thereof. ZDDP compounds generally are of the formula Zn[SP(S)(OR¹)(OR²)]₂ where R¹ and R² are C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups. These alkyl groups may be straight chain or branched. The ZDDP is typically used in amounts of from about 0.4 to 1.4 wt % of the total lubricant oil composition, although more or less can often be used advantageously. Preferably, the ZDDP is a secondary ZDDP and present in an amount of from about 0.6 to 1.0 wt %, or from 0.6 to 0.91 wt % of the total lubricant composition.

Preferable zinc dithiophosphates which are commercially available include secondary zinc dithiophosphates such as those available from for example, The Lubrizol Corporation under the trade designations “LZ 677A”, “LZ 1095” and “LZ 1371”, from for example Chevron Oronite under the trade designation “OLOA 262” and from for example Afton Chemical under the trade designation “HITEC 7169”.

Dispersants

During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants may be ashless or ash-forming in nature. Preferably, the dispersant is ashless. So-called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed above form ash upon combustion.

Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

Chemically, many dispersants may be characterized as phenates, sulfonates, sulfurized phenates, salicylates, naphthenates, stearates, carbamates, thiocarbamates, phosphorus derivatives. A particularly useful class of dispersants are the alkenylsuccinic derivatives, typically produced by the reaction of a long chain substituted alkenyl succinic compound, usually a substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. Patents describing such dispersants are U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, to which reference is made for this purpose.

Hydrocarbyl-substituted succinic acid compounds are popular dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between alkenyl succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of alkenyl succinic anhydride to polyethylene amines (TEPA, tetra-ethylene penta-amine) can vary from about 1:1 to about 5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800; and Canada Pat. No. 1,094,044.

Succinate esters are formed by the condensation reaction between alkenyl succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of an alkenyl succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction between alkenyl succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305.

The molecular weight of the alkenyl succinic anhydrides used in the preceding paragraphs will typically range between 800 and 2,500 g/mol. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid, and boron compounds such as borate esters or highly borated dispersants. The dispersants can be borated with from about 0.1 to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols range from 800 to 2,500 g/mol. Representative examples are shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannich condensation products useful in this invention can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HN(R)₂ group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are well known to one skilled in the art; see, for example, U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a molecular weight number average (Mn) of from about 500 to about 5000 g/mol or a mixture of such hydrocarbylene groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components. Such additives may be used in an amount of about 0.1 to 20 wt %, preferably about 0.5 to 8 wt %.

Detergents

Detergents are commonly used in lubricating compositions. A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80 mg KOH/g. It is desirable for at least some detergent to be overbased, which means the detergent contains large amounts of a metal base that is achieved by reacting an excess of a metal compound (a metal hydroxide or oxide, for example) with an acidic gas (such as carbon dioxide). Overbased detergents help neutralize acidic impurities produced by the combustion process and become entrapped in the oil. Typically, the overbased material has a ratio of metallic ion to anionic portion of the detergent of about 1.05:1 to 50:1 on an equivalent basis. More preferably, the ratio is from about 4:1 to about 25:1. The resulting detergent is an overbased detergent that will typically have a TBN of greater than 80 mg KOH/g, such as 80 to 450; 85 to 450 or 150 to 450 mg KOH/g. Useful detergents can also have a TBN that ranges from a low of about 81 mg KOH/g, about 90 mg KOH/g, or about 100 mg KOH/g to a high of about 200, 300, or 450 mg KOH/g. Preferably, the overbasing cation is sodium (Na), calcium (Ca), or magnesium (Mg). A mixture of detergents of differing TBN can be also used.

Preferred detergents include the alkali or alkaline earth metal salts of sulfonates, phenates, carboxylates, phosphates, and salicylates. Sulfonates may be prepared from sulfonic acids that are typically obtained by sulfonation of alkyl substituted aromatic hydrocarbons. Hydrocarbon examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl and their halogenated derivatives (chlorobenzene, chlorotoluene, and chloronaphthalene, for example). The alkylating agents typically have about 3 to 70 carbon atoms. The alkaryl sulfonates typically contain about 9 to about 80 carbon or more carbon atoms, more typically from about 16 to 60 carbon atoms.

Klamann in “Lubricants and Related Products”, op cit discloses a number of overbased metal salts of various sulfonic acids which are useful as detergents and dispersants in lubricants. The book entitled “Lubricant Additives”, C. V. Smallheer and R. K. Smith, published by the Lezius-Hiles Co. of Cleveland, Ohio (1967), similarly discloses a number of overbased sulfonates that are useful as dispersants/detergents.

Alkaline earth phenates are another useful class of detergent. These detergents can be made by reacting alkaline earth metal hydroxide or oxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols may contain more than one alkyl substituent that are each independently straight chain or branched. When a non-sulfurized alkylphenol is used, the sulfurized product may be obtained by methods well known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

Metal salts of carboxylic acids are also useful as detergents. These carboxylic acid detergents may be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds may be overbased to produce the desired TBN level. Detergents made from salicylic acid are one preferred class of detergents derived from carboxylic acids. Useful salicylates include long chain alkyl salicylates. One useful family of compositions is of the following structure:

In Structure 1 above, R is a hydrogen atom or an alkyl group having 1 to about 30 carbon atoms, n is an integer from 1 to 4, and M is an alkaline earth metal. Preferred R groups are alkyl chains of at least C11, preferably C13 or greater. R may be optionally substituted with substituents that do not interfere with the detergent's function. M is preferably, calcium, magnesium, or barium. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of the hydrocarbyl-substituted salicylic acids may be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates may also be used as detergents.

Detergents may be simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See U.S. Pat. No. 6,034,039, for example.

Preferred detergents may include calcium phenates, calcium sulfonates, calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium salicylates and other related components (including borated detergents). Typically, the total detergent concentration is about 0.01 to about 6.0 wt %, or 0.01 to 4 wt %, or 0.01 to 3 wt %, or 0.01 to 2.2 wt %, or 0.01 to 1.5 wt % and preferably, about 0.1 to 3.5 wt %.

Antioxidants

Antioxidants retard the oxidative degradation of base oils during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. One skilled in the art knows a wide variety of oxidation inhibitors that are useful in lubricating oil compositions. See, Klamann in Lubricants and Related Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197, for example.

Useful antioxidants may include hindered phenols. These phenolic antioxidants may be ashless (metal-free) phenolic compounds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compounds are the hindered phenolics which are the ones which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic antioxidants include the hindered phenols substituted with C₆+ alkyl groups and the alkylene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono-phenolic antioxidants may include for example hindered 2,6-di-alkyl-phenolic proprionic ester derivatives. Bis-phenolic antioxidants may also be advantageously used in combination with the instant invention. Examples of ortho-coupled phenols include: 2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol); and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols include for example 4,4′-bis(2,6-di-t-butyl phenol) and 4,4′-methylene-bis(2,6-di-t-butyl phenol).

Non-phenolic oxidation inhibitors which may be used include aromatic amine antioxidants and these may be used either as such or in combination with phenolics. Typical examples of non-phenolic antioxidants include: alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic, aromatic or substituted aromatic group, R⁹ is an aromatic or a substituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(X)R¹² where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R⁸ may contain from 1 to about 20 carbon atoms, and preferably contains from about 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. Preferably, both R⁸ and R⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸ and R⁹ may be joined together with other groups such as sulfur.

Typical aromatic amines antioxidants have alkyl substituent groups of at least about 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than about 14 carbon atoms. The general types of amine antioxidants useful in the present compositions include diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also useful. Polymeric amine antioxidants can also be used. Particular examples of aromatic amine antioxidants useful in the present invention include: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine. Sulfurized alkyl phenols and alkali or alkaline earth metal salts thereof may also be useful antioxidants.

Preferred antioxidants include hindered phenols, arylamines. These antioxidants may be used individually by type or in combination with one another.

Antioxidants may be used in an amount of about 0.01 to 5 wt %, preferably about 0.01 to 1.5 wt %, more preferably zero to less than 1.5 wt %, most preferably zero, based on the total weight of the engine oil lubricant.

Pour Point Depressants

Conventional pour point depressants (also known as lube oil flow improvers) may be added to the compositions of the present invention if desired. These pour point depressant may be added to lubricating compositions of the present invention to lower the minimum temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479; 2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pour point depressants and/or the preparation thereof. Such additives may be used in an amount of about 0.01 to 5 wt %, preferably about 0.01 to 1.5 wt %, based on the total weight of the engine oil lubricant.

Corrosion Inhibitors (CI)

One or more corrosion inhibitors may be added to the lubricating oil compositions. Corrosion inhibitors are additives that protect lubricated metal surfaces against chemical attack by water or other contaminants. Corrosion inhibitors may also be used to reduce the degradation of metallic parts that are in contact with the lubricating oil composition. As used herein, corrosion inhibitors include anti-rust additives, metal deactivators, and metal passivators.

One type of corrosion inhibitor is a polar compound that wets the metal surface preferentially, protecting it with a film of oil. Another type of corrosion inhibitor absorbs water by incorporating it in a water-in-oil emulsion so that only oil touches the metal surface. Yet another type of corrosion inhibitor chemically adheres to the metal to produce a non-reactive surface. Suitable corrosion inhibitors include organic salts including zinc dithiophosphates, metal phenolates, neutral metal sulfonates (e.g., calcium sulfonate, magnesium sulfonate, barium sulfonate, zinc sulfonate, etc.), metal naphthenates (e.g., zinc naphthenate, barium naphthenate, calcium naphthenate, magnesium naphthenate, etc.), fatty acids and amines. Other suitable corrosion inhibitors include, for example, aryl thiazines, alkyl substituted dimercaptothiodiazoles, alkyl substituted dimercaptothiadiazoles, thiazoles, triazoles, non-ionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, anionic alkyl sulfonic acids, and the like, and mixtures thereof.

Illustrative corrosion inhibitors may include, for example, (short-chain) alkyl and alkenyl succinic acids, partial esters thereof and nitrogen-containing derivatives thereof; and petroleum sulfonates, synthetic sulfonates, synthetic alkarylsulfonates, such as metal alkylbenzene sulfonates, and metal dinonylnaphthalene sulfonates. Corrosion inhibitors also include, for example, monocarboxylic acids which have from 8 to 30 carbon atoms, alkyl or alkenyl succinates or partial esters thereof, hydroxy-fatty acids which have from 12 to 30 carbon atoms and derivatives thereof, sarcosines which have from 8 to 24 carbon atoms and derivatives thereof, amino acids and derivatives thereof, naphthenic acid and derivatives thereof, lanolin fatty acid, mercapto-fatty acids and paraffin oxides.

Particularly preferred corrosion inhibitors include, for example, monocarboxylic acids (C₈-C₃₀), caprylic acid, pelargonic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, cerotic acid, montanic acid, melis sic acid, oleic acid, docosanic acid, erucic acid, eicosenic acid, beef tallow fatty acid, soy bean fatty acid, coconut oil fatty acid, linolic acid, linoleic acid, tall oil fatty acid, 12-hydroxystearic acid, laurylsarcosinic acid, myritsylsarcosinic acid, palmitylsarcosinic acid, stearylsarcosinic acid, oleylsarcosinic acid, alkylated (C₈-C₂₀) phenoxyacetic acids, lanolin fatty acid and C₈-C₂₄ mercapto-fatty acids.

Examples of polybasic carboxylic acids which function as corrosion inhibitors include alkenyl (C₁₀-C₁₀₀) succinic acids and ester derivatives thereof, dimer acid, N-acyl-N-alkyloxyalkyl aspartic acid esters (U.S. Pat. No. 5,275,749). Examples of the alkylamines which function as corrosion inhibitors or as reaction products with the above carboxylates to give amides and the like are represented by primary amines such as laurylamine, coconut-amine, n-tridecylamine, myristylamine, n-pentadecylamine, palmitylamine, n-heptadecylamine, stearylamine, n-nonadecylamine, n-eicosylamine, n-heneicosylamine, n-docosylamine, n-tricosylamine, n-pentacosylamine, oleylamine, beef tallow-amine, hydrogenated beef tallow-amine and soy bean-amine. Examples of the secondary amines include dilaurylamine, di-coconut-amine, di-n-tri decyl amine, dimyristylamine, di-n-pentadecylamine, dipalmitylamine, di-n-pentadecylamine, distearylamine, di-n-nonadecylamine, di-n-eicosylamine, di-n-heneicosylamine, di-n-docosylamine, di-n-tricosylamine, di-n-pentacosyl-amine, dioleylamine, di-beef tallow-amine, di-hydrogenated beef tallow-amine and di-soy bean-amine. Examples of the aforementioned alkylenediamines, alkylated alkylenediamines, and N-alkylpolyalkyenediamines include: ethylenediamines such as laurylethylenediamine, coconut ethylenediamine, n-tridecylethylenediamine-, myristylethylenediamine, n-pentadecylethylenediamine, palmitylethylenediamine, n-heptadecylethylenediamine, stearylethylenediamine, n-nonadecylethylenediamine, n-eicosylethylenediamine, n-heneicosylethylenediamine, n-docosylethylendiamine, n-tricosylethylenediamine, n-pentacosylethylenediamine, oleylethylenediamine, beef tallow-ethylenediamine, hydrogenated beef tallow-ethylenediamine and soy bean-ethylenediamine; propylenediamines such as laurylpropylenediamine, coconut propylenediamine, n-tridecylpropylenediamine, myristylpropylenediamine, n-pentadecylpropylenediamine, palmitylpropylenediamine, n-heptadecylpropylenediamine, stearylpropylenediamine, n-nonadecylpropylenediamine, n-eicosylpropylenediamine, n-heneicosylpropylenediamine, n-docosylpropylendiamine, n-tricosylpropylenediamine, n-pentacosylpropylenediamine, diethylene triamine (DETA) or triethylene tetramine (TETA), oleylpropylenediamine, beef tallow-propylenediamine, hydrogenated beef tallow-propylenediamine and soy bean-propylenediamine; butylenediamines such as laurylbutylenediamine, coconut butylenediamine, n-tridecylbutylenediamine-myristylbutylenediamine, n-pentadecylbutylenediamine, stearylbutylenediamine, n-eicosylbutylenediamine, n-heneicosylbutylenedia-mine, n-docosylbutylendiamine, n-tricosylbutylenediamine, n-pentacosylbutylenediamine, oleylbutylenediamine, beef tallow-butylenediamine, hydrogenated beef tallow-butylenediamine and soy bean butylenediamine; and pentylenediamines such as laurylpentylenediamine, coconut pentylenediamine, myristylpentylenediamine, palmitylpentylenediamine, stearylpentylenediamine, oleyl-pentylenediamine, beef tallow-pentylenediamine, hydrogenated beef tallow-pentylenediamine and soy bean pentylenediamine.

Other illustrative corrosion inhibitors include 2,5-dimercapto-1,3,4-thiadiazoles and derivatives thereof, mercaptobenzothiazoles, alkyltriazoles and benzotriazoles. Examples of dibasic acids useful as corrosion inhibitors, which are used in the present disclosure, are sebacic acid, adipic acid, azelaic acid, dodecanedioic acid, 3-methyladipic acid, 3-nitrophthalic acid, 1,10-decanedicarboxylic acid, and fumaric acid. The corrosion inhibitors may be a straight or branch-chained, saturated or unsaturated monocarboxylic acid or ester thereof which are optionally sulfurized in an amount up to 35 wt %. Preferably the acid is a C₄ to C₂₂ straight chain unsaturated monocarboxylic acid. The preferred concentration of this additive is from 0.001 wt % to 0.35 wt % of the total lubricant composition. The preferred monocarboxylic acid is sulfurized oleic acid. Alternatively, other suitable materials include oleic acid itself, valeric acid and erucic acid. An illustrative corrosion inhibitor includes a triazole as previously defined. The triazole should be used at a concentration from 0.005 wt % to 0.25 wt % of the total composition. The preferred triazole is tolylotriazole which is suitably included in the compositions of the disclosure. Also suitably included in compositions are triazoles, thiazoles and certain diamine compounds which are useful as metal deactivators or metal passivators. Examples include triazole, benzotriazole and substituted benzotriazoles such as alkyl substituted derivatives. The alkyl substituent generally contains up to 15 carbon atoms, preferably up to 8 carbon atoms. The triazoles optionally contain other substituents on the aromatic ring such as halogens, nitro, amino, mercapto, etc. Examples of suitable compounds are benzotriazole and the tolyltriazoles, ethylbenzotriazoles, hexylbenzotriazoles, octylbenzotriazoles, chlorobenzotriazoles and nitrobenzotriazoles. Benzotriazole and tolyltriazole are particularly preferred. A straight or branched chain saturated or unsaturated monocarboxylic acid which is optionally sulfurized in an amount which is up to 35 wt %; or an ester of such an acid; and a triazole or alkyl derivatives thereof, or short chain alkyl of up to 5 carbon atoms; n is zero or an integer between 1 and 3 inclusive; and is hydrogen, morpholino, alkyl, amido, amino, hydroxy or alkyl or aryl substituted derivatives thereof; or a triazole selected from 1,2,4 triazole, 1,2,3 triazole, 5-anilo-1,2,3,4-thiatriazole, 3-amino-1,2,4 triazole, 1-H-benzotriazole-1-yl-methylisocyanide, methylene-bis-benzotriazole and naphthotriazole.

Other illustrative corrosion inhibitors may include 2-mercaptobenzothiazole, dialkyl-2,5-dimercapto-1,3,4-thiadiazole; N,N′-disalicylideneethylenediamine, N,N′-disalicylidenepropylenediamine, N-salicylideneethylamine, N,N′-disalicylideneethyldiamine; triethylenediamine, ethylenediaminetetraacetic acid; zinc dialkyldithiophosphates and dialkyl dithiocarbamates, and the like.

Other illustrative corrosion inhibitors may include a yellow metal passivator. The term “yellow metal” refers to a metallurgical grouping that includes, for example, brass and bronze alloys, aluminum bronze, phosphor bronze, copper, copper nickel alloys, and beryllium copper, and the like. Typical yellow metal passivators include, for example, benzotriazole, tolutriazole, tolyltriazole, mixtures of sodium tolutriazole and tolyltriazole, imidazole, benzimidazole, imidazoline, pyrimidine, and derivatives thereof, and combinations thereof. In one particular and non-limiting embodiment, a compound containing tolyltriazole is selected.

The one or more metal corrosion inhibitors may be present in amounts ranging from about 0.01 wt % to about 5.0 wt %, preferably about 0.01 wt % to about 3.0 wt %, and more preferably from about 0.01 wt % to about 1.5 wt %, based on the total weight of the engine oil lubricant composition.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricating oils include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride. Such additives may be used in an amount of about 0.01 to 3 wt %, preferably about 0.01 to 2 wt %, based on the total weight of the engine oil lubricant.

Anti-Foam

Anti-foam agents may advantageously be added to lubricant compositions. These agents retard the formation of stable foams. Silicones and organic polymers are typical anti-foam agents. For example, polysiloxanes, such as silicon oil or polydimethyl siloxane, provide antifoam properties. Anti-foam agents are commercially available and may be used in conventional minor amounts along with other additives such as demulsifiers; usually the amount of these additives combined is less than 1 wt % and often less than 0.1 wt %, based on the total weight of the engine oil lubricant composition.

When lubricating oil compositions contain any one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Illustrative amounts of such additives that can be used in the engine oil lubricants described herein are shown in Table 1 below.

Note that many of the additives are shipped from the manufacturer and used with a certain amount of base oil diluent in the formulation. Accordingly, the weight amounts in Table 2, as well as other amounts mentioned in this specification, are directed to the amount of active ingredient (that is the non-diluent portion of the ingredient). The wt % indicated below are based on the total weight of the lubricating oil composition.

TABLE 2 Typical Amounts of Various Lubricant Oil Components Approximate Approximate Compound wt % (Useful) wt % (Preferred) Detergent 0.01-6 0.01-4  Dispersant  0.1-20 0.1-8  Friction Modifier 0.01-5 0.01-1.5 Viscosity Modifier (solid  0.1-8 0.1-6  polymer basis) Antioxidant  0.1-5  0.1-2.0 Anti-wear Additive 0.01-6 0.01-4  Pour Point Depressant  0.0-5 0.01-1.5 Anti-foam Agent 0.001-3  0.001-0.15 Steel Corrosion Inhibitor 0.001-1  0.001-0.5  Base stock or base oil Balance Balance

The foregoing additives may be added independently or may be pre-combined in packages which can be obtained from suppliers of lubricant oil additives. Additive packages with a variety of ingredients, proportions and characteristics are available and selection of the appropriate package will take the requisite use of the ultimate composition into account. The additive package may be incorporated into the engine oil lubricant compositions at loadings of about 9 wt % to about 15 wt %, or about 10 wt % to about 14.5 wt %, or about 11 wt % to about 14 wt %, based on the total weight of the lubricant composition.

Examples

The foregoing discussion can be further described with reference to the following non-limiting examples. In the examples that follow, the effects on fuel economy and thus CO₂ emissions of 0.5 wt % sulfated ash 5W-30 base formulations (i.e. “low ash” formulations) were studied using an organic friction modifier in combination with different detergents and corrosion inhibitors.

Two 0.5 wt % sulfated ash 5W-30 base formulations were prepared, Base Formulation 1 (“BF1”) and Base Formulation 2 (“BF2”). BF1 and BF2 were identical except that BF2 further included 0.7 wt % of a mixed glyceride friction modifier. Both BF1 and BF2 were formulated with a 64 mg KOH/g ASTM D2896 TBN calcium salicylate detergent (2.3% Ca) as the only detergent additive. Table 3 summarizes the BF1 and BF2 formulations as well as the measured ash content and fuel economies for each.

TABLE 3 Lubricant formulation and fuel economy test results Base Formulation 1 Base Formulation 2 (“BF1”) (“BF2”) Base oil, wt % 77.34 76.64 Mixed Glyceride Friction 0.7 Modifier, wt % 64 mg KOH/g Calcium 4.4 4.4 Salicylate Detergent, wt % Other Additives, wt % 18.26 18.26 KV100, ASTM D445, cSt 11.3 10.9 HTHS150, ASTM D4683, cP 3.18 3.25 CCS-35C, ASTM D5293, cP 6975 7280 ASTM D5185 Ca, ppm 1000 1000 ASTM D5185 B, ppm 92 92 ASTM D5185 Mg, ppm 0 0 ASTM D5185 Mo, ppm 180 180 ASTM D5185 Zn, ppm 830 830 ASTM D5185 P, ppm 770 770 ASTM D874 Ash, wt % 0.51 0.51 ASTM D8114 VIE FEI 1, % 1.4 2.1 ASTM D8114 VIE FEI 2, % 2.9 4.6

The ash content was measured according to ASTM D874. Sulfated ash values were calculated using the following factors (F): Ca—3.4, Mg—4.95, B—3.22, Zn—1.25, Mo—1.5. where calculated sulfated ash is given by Equation 1.

Calculated Sulfated Ash (weight %)=ΣM _(i) ·F _(i)  Eq. 1

Where M_(i) equals the metal concentration in weight % and F_(i) equals the sulfated ash factor for the metal.

Table 3 shows that the presence of the mixed glyceride friction modifier in BF2 produced a significant increase in fuel economy, as measured by the ASTM-D8114 Sequence VIE fuel economy test in the presence of the 64 mg KOH/g ASTM D2896 TBN calcium salicylate detergent. The initial fuel economy (FEI 1) and aged fuel economy (FEI 2) of BF2 with the 0.7 wt % of a mixed glyceride friction modifier increased significantly compared to BF1 (having none of the mixed glyceride friction modifier). Such significant increase in fuel economy necessarily results in significantly reduced CO₂ emissions.

Eight different corrosion inhibitors (Additives 1 to 8) were then added to the BF2 formulation to determine effects on corrosion protection as determined by ASTM D6557. Additive 1 was an imidazoline, which is a reaction product of oleic acid and amino-ethyl 2-ethylhexyl amine, and has no pendent organic acid groups.

Additives 2, 3, and 7 contained organic acid groups. Specifically, Additive 2 was an imidazoline reaction product of oleic acid and amino-ethyl 2-ethylhexyl amine plus free oleic acid. Additive 3 was a C16 alkylated succinic anhydride reacted with 1,3 propane diol. Additive 7 was an ashless ester/amide/carboxylate having the following structure:

Additives 4, 5, 6, and 8 were organic salts (organo-metallic molecules) having ASTM D2896 total base numbers (TBN) less than 3 mg KOH/g. Specifically, Additive 4 was a barium salt of dinonyl, naphthylenesulfonic acid having a ASTM D2896 TBN of less than 1 mg KOH/g and a Ba content of 6.65 wt %. Additive 5 was zinc dinonylnaphthalene sulfonate having a ASTM D2896 TBN of 1.9 mg KOH/g and a Zn content of 2.9 wt %. Additive 6 was zinc naphthenate having a ASTM D2896 TBN of 2.9 mg KOH/g and a Zn content of 10 wt %. Additive 8 was calcium dinonylnaphthalene sulfonate having a ASTM D2896 TBN of less than 1 mg KOH/g and a Ca content of 2.1 wt %.

Table 4 summarizes the lubricant formulations and ball rust test results measured according to ASTM D6557. All weights are wt % based on the total weight of the lubricant.

TABLE 4 Formulation Summary for ASTM D6557 BRT Testing (AGV). TABLE 4 ADDITIVE BF2 1 2 3 4 5 6 7 8 BRT AGV CEx.1 100 33 CEx.2 99.5 0.5 19 CEx.3 99.0 1.00 40 Ex.1 99.95 0.05 72 Ex.2 99.8 0.20 76 Ex.3 99.5 0.5 76 Ex.4 99.0 1.00 60 Ex.5 99.95 0.05 62 Ex.6 99.8 0.20 62 Ex.7 99.5 0.5 77 Ex.8 99.0 1.00 79 Ex.9 99.5 0.50 66 Ex.10 99.0 1.00 57 Ex.11 99.5 0.50 74 Ex.12 99.0 1.00 82 Ex.13 99.95 0.05 74 Ex.14 99.8 0.20 74 Ex.15 99.5 0.5 76 Ex.16 99.0 1.00 88 Ex.17 99.95 0.05 52 Ex.18 99.8 0.20 60 Ex.19 99.5 0.5 70 Ex.20 99.0 1.00 52 Ex.21 99.95 0.05 74 Ex.22 99.8 0.20 74 Ex.23 99.5 0.5 68 Ex.24 99.0 1.00 65

The ASTM D6557 steel corrosion performance for Base Formulation 2 was 33 AGV. This is considered a poor result; however, this is not unexpected because the formulation ash level of 0.5% was low. As seen in Table 4 above, the addition of 1 wt % of the Additives 1 to 8 to Base Formulation 2 improved the steel corrosion performance (AGV) to 40, 60, 79, 57, 82, 88, 52, and 65, respectively. The AGV results with Additives 2 through 8 were significantly improved. Only the 0.5 wt % addition of Additive 1 did not improve the steel corrosion performance (AGV decreased to 19).

The addition of 0.5 wt % of each Additive 1 to 8 changed the AGV results to 19, 76, 77, 66, 74, 76, 70, and 68 AGV respectively. Additive 1 did not improve the corrosion performance. The results for Additives 2 through 8 were significant improvements.

The addition of 0.2 wt % of Additives 2, 3, 6, 7, and 8 significantly improved the AGV results to 76, 69, 64, 60, and 74 AGV respectively.

The addition of 0.05 wt % of Additives 2, 3, 6, 7, and 8 changed the AGV results to 72, 62, 74, 52, and 74 AGV respectively, which are significant improvements and similar to the improvements gained by the 0.2 wt % addition of these same additives.

Two other detergents were studied in combination with Additive 3 (C16 alkylated succinic anhydride, reacted with 1,3 propane diol) in a 0.5 wt % sulfated ash 5W-30 base formulation (“BF3”). In these examples, BF3 was similar to BF2, except the 64 mg KOH/g TBN calcium salicylate detergent in BF2 was replaced with a 405 mg KOH/g TBN magnesium sulfonate detergent and a 300 mg KOH/g TBN calcium sulfonate detergent in the amounts reported below in Table 5. The 405 mg KOH/g TBN magnesium sulfonate detergent contained 9.1 wt % Mg and the 300 mg KOH/g TBN calcium sulfonate detergent contained 11.6 wt % Ca. The amount of each detergent was selected to provide a sulfated ash value of 0.5% to the fully formulated lubricant. To these formulations, 0.05 wt % of Additive 3 was used.

TABLE 5 Alternate Detergent Combinations Evaluated in the BRT CEx.4 CEx.5 CEx.6 Ex.25 Ex.26 Ex.27 Base oil, wt % 80.28 80.17 80.23 80.23 80.12 80.18 Mixed Glyceride  0.7  0.7  0.7  0.7  0.7  0.7 Friction Modifier, wt % Other additives, wt % 18.26 18.26 18.26 18.26 18.26 18.26 Additive 3, wt %  0.05  0.05  0.05 Mg Sulfonate, 405 TBN, wt %  0.76  0.38  0.76  0.38 Ca Sulfonate, 300 TBN, wt %  0.87  0.43  0.87  0.43 BRT AGV, % 41 29 33 47 35 39

These additives were then tested to determine their effectiveness on corrosion protection as determined by the ASTM D6557 ball rust test (ASTM D6557 BRT).

With the 405 mg KOH/g TBN magnesium sulfonate detergent (CEx.4), the BRT result was 41. Adding 0.05 wt % of Additive 3 (Ex. 25) increased the BRT result from 41 to 47 AGV. With the 300 mg KOH/g TBN calcium sulfonate detergent (CEx.5), the BRT result was 29. Adding 0.05 wt % of Additive 3 (Ex.26) increased the BRT result from 29 to 35 AGV. With a mix of the 405 mg KOH/g TBN magnesium sulfonate detergent and the 300 TBN calcium sulfonate detergent (CEx.6), the BRT result was 33. Adding 0.05 wt % of Additive 3 (Ex.27) increased the BRT result from 33 to 39 AGV.

These formulations show the additives that provided a BRT benefit for the Ca salicylate (Ex. 1 to 24) also provided a benefit for either Mg sulfonate (Ex. 25), Ca sulfonate (Ex. 26), or a mix of Mg sulfonate and Ca sulfonate (Ex. 27). This is a significant benefit for formulating engine oils with all magnesium or calcium or a mix of magnesium and calcium.

It was also unexpected that the organic salt (organo-metallic) naphthalene additives (Additives 4, 5, 6, and 8) with very low TBN values (less than 3 mg KOH/g) were effective in the ball rust test that is performed in the presence of organic and inorganic acids. TBN is often associated with the ability to neutralize the acidic species to prevent corrosion. The higher the TBN value, the better the ability to neutralize the acidity. Because the TBN of Additives 4, 5, 6, and 8 were less than 3 mg KOH/g, and those additives caused an increase in BRT results means these improvements were not from acid neutralization, which was nothing short of surprising and unexpected.

Even more unexpected was that Additives 2, 3, and 7 provided effective BRT results of 19 or more. Additives 2, 3, and 7 contained organic acid groups, which are known to promote corrosion such as lead corrosion. It was nothing short of surprising and unexpected that Additives 2, 3, and 7 with organic acid groups provided effective corrosion results in the presence of a calcium salicylate detergent and mixed glyceride friction modifier, which exhibited excellent fuel economy and thus lower CO₂ emissions.

Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

Various terms have been defined above. To the extent a term used in a claim can be not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure can be not inconsistent with this application and for all jurisdictions in which such incorporation can be permitted.

While certain preferred embodiments of the present invention have been illustrated and described in detail above, it can be apparent that modifications and adaptations thereof will occur to those having ordinary skill in the art. It should be, therefore, expressly understood that such modifications and adaptations may be devised without departing from the basic scope thereof, and the scope thereof can be determined by the claims that follow. 

What is claimed is:
 1. An engine oil lubricant composition, comprising: about 40 wt % to about 90 wt % of at least one base oil; about 0.1 wt % to about 5 wt % of an organic friction modifier; about 1 wt % to about 6 wt % of at least one detergent comprising magnesium or calcium; about 0.01 wt % to about 1 wt % of a corrosion inhibitor having at least one organic acid moiety or organic salt thereof; wherein the engine oil lubricant composition has a sulfated ash content of 0.5 wt % or less, and an HTHS (ASTM D4683) of less than or equal to 3.7 cP at 150° C.
 2. The lubricant composition of claim 1, wherein the composition comprises 0.1 wt % to about 1.0 wt % of an organic friction modifier.
 3. The lubricant composition of claim 1, wherein the organic friction modifier is an alkyl or alkylene glyceride ester.
 4. The lubricant composition of claim 1, wherein the at least one detergent comprises magnesium or calcium sulfonate or a mixture thereof.
 5. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having a naphthenate, naphthalene sulfonate, or at least one organic acid or organic salt moiety improves the ball rust test (ASTM D6557) average gray value (AGV) by at least 25%.
 6. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having a naphthenate, naphthalene sulfonate, or at least one organic acid or organic salt moiety improves the ball rust test (ASTM D6557) average gray value (AGV) by at least 50%.
 7. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having a naphthenate, naphthalene sulfonate, or at least one organic acid or organic salt moiety improves the ball rust test (ASTM D6557) average gray value (AGV) by at least 100%.
 8. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having at least one organic acid or organic salt of an alkyl or alkylene substituted naphthenate or naphthalene sulfonate moiety.
 9. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is zinc naphthenate.
 10. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is the barium salt of dinonyl, naphthylenesulfonic acid.
 11. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is calcium dinonylnaphthalene sulfonate.
 12. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is zinc dinonylnaphthalene sulfonate.
 13. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having at least one organic acid or organic salt of a carboxylate moiety.
 14. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is the imidazoline reaction product of oleic acid and amino-ethyl 2-ethylhexyl amine plus free oleic acid.
 15. The lubricating engine oil of claim 1, wherein the corrosion inhibitor is a sixteen carbon chain alkylated succinic anhydride reacted with 1,3 propane diol.
 16. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having at least one organic salt moiety with a counter ion from the alkali, alkaline earth, transition metal, metalloid, or post transition metal groups.
 17. The lubricating engine oil of claim 1, wherein the corrosion inhibitor having at least one organic salt moiety with a calcium, magnesium, lithium, sodium, barium, zinc, or copper counter ion.
 18. An engine oil lubricant composition, comprising: about 40 wt % to about 90 wt % of at least one base oil; about 0.1 wt % to about 5 wt % of an organic friction modifier; about 1 wt % to about 6 wt % of at least one detergent comprising magnesium or calcium; about 0.01 wt % to about 1 wt % of a corrosion inhibitor comprising an organo-metallic naphthalene compound; wherein the engine oil lubricant composition has a sulfated ash content of 0.5 wt % or less, and an HTHS (ASTM D4683) of less than or equal to 3.7 cP at 150° C.
 19. The lubricating engine oil of claim 18, wherein the corrosion inhibitor having at least one organic acid or organic salt of an alkyl or alkylene substituted naphthenate or naphthalene sulfonate moiety.
 20. The lubricating engine oil of claim 18, wherein the corrosion inhibitor is selected from zinc naphthenate, the barium salt of dinonylnaphthylenesulfonic acid, calcium dinonylnaphthalene sulfonate, and zinc dinonylnaphthalene sulfonate. 